GENERAL allows you to choose a set of entities (excluding
points) whose projections define a closed region in the
current view. Islands are permitted inside of the selected
outer perimeter.

Choose Selection Menu option to specify the desired set of
entities. As with crosshatching, islands can be chosen that
which will be excluded (or included) as required.

If the selected entities do not form a closed shape, they
are rejected. Press <Enter> to continue. Choose from the
Selection Menu again, and reselect desired entities.

Rectangular shapes (referred to as panels) are used to
approximate the area of the selected shape. The area and
centroid values are calculated by summing up the area and
centroids for each panel within the shape. These panels 
are stacked sequentially through the shape and are sized
according to the assigned panel width value.

A smaller width value generates more panels within the
shape, therefore adding more accuracy to the area and
centroid calculated.

The area for the closed shape is calculated and displayed.
Press <Enter> again to display the X and Y coordinates of
the centroid, with respect to the view coordinate system
(XV, YV). A temporary asterisk (*) is displayed at the
centroid location.
